requesttype=0x23

Issued after Identify Camera

Command: 0x50 bytes.

00000000  10 00 00 00 01 02 00 00 00 00 00 00 00 00 00 00  ................
00000010  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
00000020  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
00000030  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
00000040  02 00 00 00 23 00 10 12 10 00 00 00 f0 df e4 00  ....#...........
      

Response: 0x58 bytes

00000000  18 00 00 00 01 03 00 00 00 00 00 00 00 00 00 00  ................
00000010  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
00000020  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
00000030  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
00000040  02 00 00 00 23 00 10 22 18 00 00 00 f0 df e4 00  ....#.."........
00000050  00 00 00 00 0e 46 03 1f                          .....F..
      

The 4 bytes at 0x50 are presumably a status code (0 for success); the next four bytes are the camera Body ID (hardware serial number) in binary. Printing this number as a 10-digit decimal with leading zeroes gives the Camera Body No. seen in the EOS Viewer Utility. This camera has a body ID of 0520308238.